1. Technical Field
Embodiments of the present disclosure relate to a semiconductor device capable of controlling a refresh operation and a semiconductor system.
2. Related Art
Among semiconductor devices, a DRAM (dynamic random access memory) has a characteristic such that information stored in memory cells of the DRAM disappear as time goes by, unlike an SRAM (static random access memory) or a flash memory. In order to prevent such a phenomenon, an operation of rewriting information stored in memory cells of the DRAM is performed from outside the DRAM within a predetermined period. Such an operation is referred to as a refresh. The refresh is performed in such a way as to activate each word line at least one time within a retention time of memory cells or the like and sense and amplify data. The retention time refers to a time during which data can be retained in a memory cell without a refresh after the data is written to the memory cell.
Meanwhile, the retention time of a memory cell is substantially changed depending upon a temperature of a semiconductor device. Therefore, it may be necessary to adjust operating conditions of circuit blocks of a semiconductor system, according to a change in the internal temperature of the semiconductor device. In order to adjust operating conditions according to a change of the internal temperature of a semiconductor system, temperature sensors such as a DTSR (digital temperature sensor regulator), an ATSR (analog temperature sensor regulator), and a TCSR (temperature compensated self-refresh).